Conventionally, as a device to measure magnetism emitted from a living body, a biomagnetism measuring device using SQUID (Superconducting Quantum Interference Device) sensors has been researched (Patent Documents 1 to 5 or the like). By arranging a large number of SQUID sensors, and using the SQUID sensors to measure the biomagnetism, two-dimensional magnetism information, such as magnetoencephalograms and magnetocardiograms, can be obtained.
To measure the biomagnetism with the SQUID sensors, the SQUID sensors need to be maintained in a superconductive state with a refrigerant. Hence, the SQUID sensors are placed in a Dewar flask where a refrigerant is stored, and used for the measurement in a state in which the SQUID sensors are soaked in the refrigerant.
There has been proposed a biomagnetism measuring device in which a portion of an outer wall part of a refrigerant tank of a Dewar flask is formed in a shape fit for a measurement target part of a living body, such as a skull, many SQUID sensors are arranged in the outer wall part so as to be soaked in a refrigerant, and the outside of the outer wall part touches the living body, and consequently the SQUID sensors are close to the living body with a certain distance, and the measurement is performed so that a magnetoencephalogram or the like can be obtained.